There is no option to report someone filing your dependent on their tax return. All you need to do is file your tax return with the child as your dependent. If you have a tax refund the IRS will pay you the refund. You will have to print and mail the tax return if the someone filed first with the dependent.
Within a year the IRS will investigate and send you and the other party a letter in the mail. The loser of the investigation has to pay back any tax refund plus penalties and interest.
